In recent years, as to printed wiring boards, increase in a number of layers has been advancing in order to respond to reduction in size, thickness and the like of electronic devices and electronic components. A so-called multilayer printed wiring board is being manufactured by stacking a circuit board for outer layer or a copper foil on a circuit board for inner layer, which is provided with a circuit composed of a copper foil or the like on one side or both sides, through a prepreg, and integrating them.
By the way, in such a multilayer printed wiring board, it is an important problem to ensure a bonding property between a copper circuit formed on the circuit board for inner layer and an insulating adherent resin of the prepreg for stacking the circuit board for outer layer or copper foil.
Patent Document 1 discloses an invention relating to a copper foil surface treatment agent which improves a bonding property between a copper foil and a prepreg and solder heat resistance of a copper-clad laminate obtained by bonding the copper foil to the prepreg.
This document discloses the combination use of a trialkoxysilane compound having an imidazole ring with a tetraalkoxysilane compound as components of the surface treatment agent.
Patent Document 2 discloses an invention relating to a copper surface conditioning composition and a surface treatment method, which can maintain an adhesion property between copper and an insulating material such as a resin without performing a roughening treatment such as etching of a surface of copper.
This document discloses that silane coupling agents having an alkoxy group, such as silanol and trisilanol is preferred as a component of the surface conditioning composition in view of an excellent adhesion property to an insulating material and that, among them, a silane coupling agent having a mercapto group is preferred in view of improving an adhesion property between copper and an insulating material such as an epoxy resin.
Also, it is disclosed that a solution containing the surface conditioning composition is able to be prepared by dissolving the composition in a mixed solvent of water and an organic solvent. Further, it is disclosed that after bringing the solution into contact with a surface of copper, drying may be performed after washing with water or drying may be performed without washing with water, and that in the case of performing the drying after washing with water, a film having an uniform thickness can be obtained, on the other hand, in the case of performing the drying without washing with water, a high adhesion property to the insulating material can be obtained.
Patent Document 3 discloses an invention relating to a production method of a silane coupling agent solution, a silane coupling agent solution, a surface treatment method of a base material using the same, and the like.
This document discloses that by mixing an organic silicon compound with water to sufficiently form silanol groups and then further mixing with an alcohol, a high silanolation rate can be actualized, uniform coating is possible and excellent adhesion property can be actualized, and that the silanolation rate is preferably from 60 to 100%, and more preferably from 80 to 100%.
Also, as the organic silicon compound, 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane are disclosed.
The problem of the invention is to improve an adhesion property between a base material composed of an organic polymer compound or an inorganic material and a liquid crystalline compound, and there is no mention about an adhesion property in the case where copper is the base material.
Patent Document 4 discloses an invention relating to a silane coupling agent and a polymer composition.
This document discloses, as a component of a silane coupling agent used as a primer for bonding glass or metal to rubber, various substances having a structure where a nitrogen-containing heterocyclic ring such as triazole or thiazole is connected to a silyl group such as a trimethoxysilyl group or a triethoxysilyl group, through an organic group having a thioether (sulfide) bond or the like.